This one has me pretty stumped. I've got an XR650R that at high revs starts blowing oil out the crankcase vent. I know most of you are thinking it's over filled but it's not, it's got 1.75 qts. And it's not blowing out the counter shaft seal ether. The oil pump check valve has been replaced as well as the oil pump and the right side crank seal and the problem continues. The bike has a fresh Wiseco 11:1 piston but it had the problem before the top end was done. The only other thing I can think of is maybe the sump reed valve is broken. Have any of you guys seen this before? It only does it when the bike is taken on the freeway. It's the damnest thing. If anyone has any insight I'm all ears. Thanks for any input guys.